Stability (CV value, coefficient of variation): Stability is a crucial indicator of a blood glucose meter's quality. Because blood glucose meters have relatively large errors-for example, a blood glucose level of 10 might show a reading of 8 or 12 according to national standards, both considered accurate-if a single machine produces both results, it indicates poor stability. Poor stability leaves users confused and hinders effective patient guidance. Therefore, the stability of a blood glucose meter is paramount. A stable reading indicates good enzyme stability in the test strips. Manufacturers with more advanced enzyme cultivation technology generally offer products with better stability.
Accuracy (SD value, standard deviation, correlation coefficient): Good test strip stability allows for calibration, adjusting the calibration code to approximate the standard value. Accuracy depends on stability; without stability, accuracy is impossible. Calibration standards and technologies vary among manufacturers; high accuracy indicates superior calibration technology.
Setting the password technology: As a biochemical product, the cultivation process of glucose oxidase (hereinafter referred to as enzyme) is very complex, so the characteristics of each batch of enzyme will be somewhat different, resulting in slight differences in the generated current. In order to make the measurement results of each batch of test strips as close as possible to the standard value, researchers will adjust the differences between different batches of test strips by setting a password, so that each batch of test strips is as close to the standard value as possible. Therefore, setting the correct password is very important. The enzyme cultivation and password setting technologies of each manufacturer are different, which will affect the quality of each product.
Batch-to-batch variation: Due to the extremely strict environmental requirements of the blood glucose test strip production process, manufacturers calibrate to make the measured values as close to the standard values as possible. However, the difference between different batches of test strips will inevitably be greater than the difference between test strips within the same batch. This is the batch-to-batch variation; generally, the stability of test strips within the same batch is better than the stability between different batches. Our national standard requires that the batch-to-batch variation not exceed 15%.
Temperature compensation technology: Because enzymes are active, their activity generally does not change much above 20 degrees Celsius, and below 20 degrees Celsius, the lower the temperature, the lower the activity. Decreased activity results in a smaller current generated when reacting with glucose, thus lowering the measurement result. To obtain accurate blood glucose values at different temperatures, researchers use a thermistor to adjust the instrument's resistance value according to the real-time temperature, thereby ensuring that the enzyme and blood produce a current that matches the blood glucose value as closely as possible at different temperatures, thus obtaining the correct blood glucose reading. This is the temperature compensation of the blood glucose meter. Because different manufacturers use different enzyme formulations for their blood glucose test strips, each manufacturer sets its own temperature compensation parameters based on the characteristics of its enzymes. However, since the characteristics of enzymes are difficult to control, the temperature compensation effects vary considerably. Generally speaking, the closer the results obtained under different temperature conditions, the more advanced the manufacturer's temperature compensation technology.
Applicable Temperature: Because enzymes are affected by temperature, blood glucose can only be measured under specific temperature conditions. The level of temperature compensation technology from different manufacturers not only determines the stability at high and low temperatures but also the applicable temperature range of the blood glucose meter. The operating temperature range varies slightly between different blood glucose meters, generally between 10-40 degrees Celsius.
